Indeed, it is known that, in order to abruptly alter the trajectory of a missile, a guidance unit is used comprising a plurality of lateral nozzles which are distributed around the structure of said missile and the flow of the gas jet of which may be deflected by a mechanical member linked to each lateral nozzle and controlled by an actuating device. The latter generally comprises a controllable distributor through which the gas jet coming from the main propulsion generator of the missile or from an auxiliary generator, and supplying the nozzles, can pass. The distributor acts, by means of the gas jet, on the mechanical member which enables, by its change in position, the gas jet originating from the corresponding lateral nozzle to be deflected in order thus to alter the trajectory of the missile.
Although these control devices are widely used for the force guidance of missiles, risks of malfunction may arise within the distributor and the member to be controlled because of the particularly harsh fluid medium to which they are subjected, due to the high pressure and to the high temperature of the gas jet expelled from the generator.